I think your setup is doing exactly what it is supposed to be doing. So, that's a win.
The only solution I can think of is a larger turbo. The H1e is a nice size turbo for a 4 cylinder, but the SC, like stated earlier, is going to make your engine behave like a larger displacement engine.
I think an HX40 is in your future 
I'm all about a bigger turbo!
But I want to add that many Saab turbos from the early 00s use a wastegate controller that takes boost (at compressor housing) and map (after throttle plate) and uses a pwm soelnoid to combine the two pressure signals and control the wastegate. It's essentially the same thing as one of those 'leak valve' manual boost controllers except the computer has 100% control of the size of the leak at any given time.
If you had something like that you may be able to have better wastegate control with an ECU.
I have so little room left in there a bigger turbo may not fit. I like that its spooling early. Just need a more progressive bypass method thats not so on/off.
Robbie said:I'm all about a bigger turbo!
But I want to add that many Saab turbos from the early 00s use a wastegate controller that takes boost (at compressor housing) and map (after throttle plate) and uses a pwm soelnoid to combine the two pressure signals and control the wastegate. It's essentially the same thing as one of those 'leak valve' manual boost controllers except the computer has 100% control of the size of the leak at any given time.
If you had something like that you may be able to have better wastegate control with an ECU.
Chrysler had a similar solution on their turbo cars in the eighties. They leveraged the VSS and a boost control solenoid controlled by a PWM on the ECU to limit boost in 1st gear. It’s how they kept the GLHS under warranty with their transaxles made from glass and 175bhp//175lbft surging through a transaxle designed for a 80bhp engine. On the cars with the better transaxles, they softened the boost build to reduce torque steer and make them feel more like bigger engines instead of peaky boosted engines.
They also did things like alter cooling fan on/off points based on vehicle speed among other neat things. Kinda impressive when you look at how little processing power they had (you can hear the idle sag if you try and sample too much data via the diagnostic connector).
Put the throttle body upstream of the supercharger instead of downstream. No need for a bypass valve.
In reply to Knurled. :
That's how it should work, like all oem chargers having the throttle body before and putting the charger within MAP right on the inlet manifold.
Having a large fmic (that I really cannot do without) and the charger on the otherside of the engine bay with all the pipework throttle response would be a mess. Tried that before on a previous project and the delay was annoying. Especially at decel when it would maintain revs until it sucked all the extra air after the throttle body into the cylinders, and all the silicone couplers caved in! Lol.
Stefan said:Robbie said:I'm all about a bigger turbo!
But I want to add that many Saab turbos from the early 00s use a wastegate controller that takes boost (at compressor housing) and map (after throttle plate) and uses a pwm soelnoid to combine the two pressure signals and control the wastegate. It's essentially the same thing as one of those 'leak valve' manual boost controllers except the computer has 100% control of the size of the leak at any given time.
If you had something like that you may be able to have better wastegate control with an ECU.
Chrysler had a similar solution on their turbo cars in the eighties. They leveraged the VSS and a boost control solenoid controlled by a PWM on the ECU to limit boost in 1st gear. It’s how they kept the GLHS under warranty with their transaxles made from glass and 175bhp//175lbft surging through a transaxle designed for a 80bhp engine. On the cars with the better transaxles, they softened the boost build to reduce torque steer and make them feel more like bigger engines instead of peaky boosted engines.
They also did things like alter cooling fan on/off points based on vehicle speed among other neat things. Kinda impressive when you look at how little processing power they had (you can hear the idle sag if you try and sample too much data via the diagnostic connector).
I could pwm a boost only ref to the underside of the bypass wastegate diaghphram. This could keep the valve from shutting so suddenly.
Ill be over here scraching me head.... !
This is the kind of project that I think is REALLY cool. I wish GRM would do more tech articles on things like this. Not every issue but every now and then.
We have had some GREAT discussions around this build but they are spread over several threads. Maybe search by OP's username and the threads he has started to find them all, but there's a lot of good reading just in the threads he has started about this subject.
I think your setup is doing exactly what it is supposed to be doing. So, that's a win.
I agree!
Congrats CraigoryPeck for actually pulling off your 'crazy idea' and making it pretty damn nice looking in the process!! And it (mostly) works!
I agree this is mostly a 'turbo is too small' problem. Diesel turbos are made to spool on engines with pretty terrible VE and low revs, so they tend to be on the small side for a gas engine even half the size. It seems that your turbo is basically 'mostly spooled up' even in vacuum.
You could probably create some control device that would dance around this problem and it might even be 'good enough', BUT...
Given that you said sub-10 second 1/4 and i think this setup must be in a car thats around or over 3000lbs, I think you're going to be running that H1c maxed out to even get close. So, you probably need a compressor wheel upgrade. Going to a heavier compressor wheel will slow your spool somewhat. You can also clip the turbine wheel which would slow the spool further.
Given that A. Your stated goal probably requires a turbo upgrade, B. The upgrade will slow the transient response of the turbo, and C. You've already built a beautiful functional setup with the turbo 'frame' you have now, i think internally modifying the existing turbo is the best long-term approach. Put a heavier compressor wheel, clip the turbine wheel, and see if that's enough. No changes to all the fab work you've already done!
If it's NOT enough, you might try retarding the camshaft a little. Your positive displacement blower is going to keep the low end fairly strong, but retarding the cam can soften the 'hit' of the turbo while not giving up any power that you actually care about (part throttle <3k rpm).
If you want to try something 'right now', I would just put a restrictor in the line to the bypass valve to slow its operation. The catch is it would slow it both ways unless you built a one way check valve into it. A common manual boost controller is basically an adjustable spring loaded one-way check valve with an orifice on one side to bleed off pressure trapped between the check valve and the wastegate. You need that basic thing but with the check valve flipped OR the orifice on the other side. That way it could allow the bypass to open quickly by opening the check valve under vacuum, but once vacuum was gone the the check valve would seat and air coming in to let the bypass valve close would have to flow through the tiny orifice. There are many writeups on how to build your own boost controller using the brass fittings section at the hardware store. The thing you need would have all the same parts, just have the orifice drilled in a different place. Or, you could use a regular inline vacuum check valve and T off after it with one of the off-the-shelf manual boost controllers that is just a needle valve regulating an air leak (normally on a wastegate it would be leaking OUT, yours would be leaking IN). That way the bleed itself would be adjustable rather than a fixed hole drilled in a part.
Or some combination of all three ideas!
Vigo said:This is the kind of project that I think is REALLY cool. I wish GRM would do more tech articles on things like this. Not every issue but every now and then.
We have had some GREAT discussions around this build but they are spread over several threads. Maybe search by OP's username and the threads he has started to find them all, but there's a lot of good reading just in the threads he has started about this subject.
I think your setup is doing exactly what it is supposed to be doing. So, that's a win.
I agree!
Congrats CraigoryPeck for actually pulling off your 'crazy idea' and making it pretty damn nice looking in the process!! And it (mostly) works!
I agree this is mostly a 'turbo is too small' problem. Diesel turbos are made to spool on engines with pretty terrible VE and low revs, so they tend to be on the small side for a gas engine even half the size. It seems that your turbo is basically 'mostly spooled up' even in vacuum.
You could probably create some control device that would dance around this problem and it might even be 'good enough', BUT...
Given that you said sub-10 second 1/4 and i think this setup must be in a car thats around or over 3000lbs, I think you're going to be running that H1c maxed out to even get close. So, you probably need a compressor wheel upgrade. Going to a heavier compressor wheel will slow your spool somewhat. You can also clip the turbine wheel which would slow the spool further.
Given that A. Your stated goal probably requires a turbo upgrade, B. The upgrade will slow the transient response of the turbo, and C. You've already built a beautiful functional setup with the turbo 'frame' you have now, i think internally modifying the existing turbo is the best long-term approach. Put a heavier compressor wheel, clip the turbine wheel, and see if that's enough. No changes to all the fab work you've already done!
If it's NOT enough, you might try retarding the camshaft a little. Your positive displacement blower is going to keep the low end fairly strong, but retarding the cam can soften the 'hit' of the turbo while not giving up any power that you actually care about (part throttle <3k rpm).
If you want to try something 'right now', I would just put a restrictor in the line to the bypass valve to slow its operation. The catch is it would slow it both ways unless you built a one way check valve into it. A common manual boost controller is basically an adjustable spring loaded one-way check valve with an orifice on one side to bleed off pressure trapped between the check valve and the wastegate. You need that basic thing but with the check valve flipped OR the orifice on the other side. That way it could allow the bypass to open quickly by opening the check valve under vacuum, but once vacuum was gone the the check valve would seat and air coming in to let the bypass valve close would have to flow through the tiny orifice. There are many writeups on how to build your own boost controller using the brass fittings section at the hardware store. The thing you need would have all the same parts, just have the orifice drilled in a different place. Or, you could use a regular inline vacuum check valve and T off after it with one of the off-the-shelf manual boost controllers that is just a needle valve regulating an air leak (normally on a wastegate it would be leaking OUT, yours would be leaking IN). That way the bleed itself would be adjustable rather than a fixed hole drilled in a part.
Or some combination of all three ideas!
Hey Vigo.
Thanks for the kinds words! Its great to have someone more knowledgeable than me chime in with encouragement and understand what I'm trying to do.
My car in stock form is 2500lbs plus ive put an 8.8 and watts linkage and other "stuff" in so probably 2750 at a guess..
I really dont know much about turbos and I based this around the fact the turbo came from a 6.0.. So surely ill be on the safe side regarding compressor flow, I was actually more obsessed with the exhaust turbine housing.. And getting the largest exhaust housing I could find to slow the spool and be the least restrictive as possible.
I need to actually look into those turbo mods you have mentioned as I kinda don't want to switch in a bigger turbo yet.. Everthing is custom built to fit so its well tight in there!
The camshaft I have is from an NA ranger so it does require being retarded 4 degrees to resemble the events of the stock turbo cam, so long story short I have an adjustable cam gear and can go further with no issue.
Its so funny cause since I last posted I was out test driving doing something similar to what you mentioned above.. I plumbed boost only to the lower side of the bypass wastegate but I put a tiny bleed hole in the line so the there would be a small differential that would slow the closing of the valve.. Yeah it kinda worked but wouldn't hold the same boost level as being open to atmo..
Your boost controller idea seems the best.. I was trying to work out how to do just that with a mechanical device rather than electric wizardry, I was heading down a small duck bill valve type route that would leak slowly for closing but fully open the other way to activate bypassing quickly! I can only image what would bust if it didn't bypass quick enough. My cheapo fmic already has a bulge in it.
So your in first place now in regards to what may be the solution..!
Ill order a cheapo manual boost controller so i can study that and work it in there.
This doesn't sound like a boost control issue to me. You really shouldn't have a problem if the turbo is spoiling "too fast." If anything, a quick spooling turbo is easier to control than a lazy one. I think the problem lies in either the throttle body itself, the linkage, or the tuning on throttle tip in. What kind of throttle body are you using? Is the linkage linear or progressive?
You mentioned that total boost is 20 psi after the supercharger. Have you tried running another boost gauge after the turbo, but before the supercharger? That may give you a better picture of how the turbo is spooling.
I once hooked up a boost gauge on "wrong" side of the throttle plate to see what the turbo was doing at part throttle. It was surprising how easily the turbo pressurized the intercooler piping when cruising. Based on that experience, I'd say that making boost quickly is normal, and should not be the cause of your drivability issues. Also, think of a turbo car being driven hard, on a racetrack for instance. The turbo pretty much always stays spooled, and if anything a turbo engine is more predictable and easier to drive in that situation.
Boost_Crazy said:This doesn't sound like a boost control issue to me. You really shouldn't have a problem if the turbo is spoiling "too fast." If anything, a quick spooling turbo is easier to control than a lazy one. I think the problem lies in either the throttle body itself, the linkage, or the tuning on throttle tip in. What kind of throttle body are you using? Is the linkage linear or progressive?
You mentioned that total boost is 20 psi after the supercharger. Have you tried running another boost gauge after the turbo, but before the supercharger? That may give you a better picture of how the turbo is spooling.
I once hooked up a boost gauge on "wrong" side of the throttle plate to see what the turbo was doing at part throttle. It was surprising how easily the turbo pressurized the intercooler piping when cruising. Based on that experience, I'd say that making boost quickly is normal, and should not be the cause of your drivability issues. Also, think of a turbo car being driven hard, on a racetrack for instance. The turbo pretty much always stays spooled, and if anything a turbo engine is more predictable and easier to drive in that situation.
My throttle body is from a yb cosworth, its non linear with most of the blade movement is at the end of pedal travel.
I have 3 pressure gauges. 1 for total boost, 1 inbetween the turbo and charger and another in the exhaust manifold before turbo.. Really need to see what's going on as i want total boost to exceed turbo back pressure.
Hopefully I can get out today and get some data. I can display how little the TPS moves and what happens to the rpm and boost.
I think h1cs did have a 1-year-only 21cm turbine housing. I have driven a stock truck with one. It spooled so slow its no wonder they downsized it afterwards.. and that was with all 5.9L!
Bear with me if you can!
I hooked up another boost gauge to the cold side of throttle body. So after charger and before throttle body.
I see now why my fmic has a bulge in it. Its maxing out the 30 psi boost gauge at part throttle events.
If I WOT, the boost before and after the throttle body climb in a similar fashion but if I feather it onto boost the differential between the two sides is phenomenal. I could be at 7-8psi MAP with 30+ psi on the other side of throttle blade. That explains the influx of boost at little throttle movement.
So I have another thing I need to try with my bypass waste gate.
Ill be back later!
Question. Can I reference MAP for a the turbo wastegate? Its normal to use positive pressure only but as mine is all over the show I wanna use MAP. It'll receive vacuum too but sure what odds??
Instead of slowing the turbo spool, how about dropping the speed of the supercharger with a larger pulley? It sounds like you get pretty much instance boost anyway. So why not lower the blower part of the equation and raise the turbo side? That should lower the boost under cruise and make make it more progressive.
Otherwise, can you recam the throttle linkage to make it even more progressive?
In reply to Craigorypeck :
Question. Can I reference MAP for a the turbo wastegate? Its normal to use positive pressure only but as mine is all over the show I wanna use MAP. It'll receive vacuum too but sure what odds??
I think you will end up with a lot more boost, all else being equal. The wastegate right now is seeing boost at light throttle. If you move the signal to the manifold, it will raise the boost, which is then compounded by the supercharger. You can lower it back down, but you will get a lag in control from the manifold signal. I'd predict more boost and big spikes, all else being equal.
Boost_Crazy said:Instead of slowing the turbo spool, how about dropping the speed of the supercharger with a larger pulley? It sounds like you get pretty much instance boost anyway. So why not lower the blower part of the equation and raise the turbo side? That should lower the boost under cruise and make make it more progressive.
Otherwise, can you recam the throttle linkage to make it even more progressive?
Yes that is also a possibility, but I dont want to lose the compounding factor I have. As it stands now my total MAP at WOT is more than the exhaust back pressure which is the whole point of this (probably pointless) exercise. If i drop my drive ratio I may lose that characteristic and then I'm pretty much back to being a turbo only the motor with a charger beating the crap outta the boost!
So for anyone still interested. I have it working pretty well now.
Bypass wastegate has MAP to top side of diaghphram. Bottom side is boost only. (This is how it was plumbed from the very start but wouldn't hold boost)
I put a small bleed hole in the boost only ref line that supplies the underside of diaghphram. This keeps the underside slighly under pressured enough to allow the valve to close progressively and avoid those massive boost spikes I was getting with MAP only ref to the topside, but also have the ability to stay shut and avoid the leak...
I also put a 3 port mac valve in the lower boost line. At 95% throttle position the valve activates and blocks boost to the underside of the wastegate (and the bleed hole), and vents the underside of wastegate to atmo.. SO, at full throttle the wastegate gets all pressure to topside, none to bottom side and the bleed hole is also out of the loop.
Just need to cap the total amount of boost made now as I'm just bouncing off the over boost limiter protection on the ecu.!
White line is RPM
Red line is MAP
Green is TPS
22.3psi boost.
Comes in pretty hard.
I see now why my fmic has a bulge in it. Its maxing out the 30 psi boost gauge at part throttle events.
If I WOT, the boost before and after the throttle body climb in a similar fashion but if I feather it onto boost the differential between the two sides is phenomenal. I could be at 7-8psi MAP with 30+ psi on the other side of throttle blade. That explains the influx of boost at little throttle movement.
Apparently i forgot this thread existed for a few days!! Whoops. Anwyay, it seems like that problem is probably due to you having the turbo blowing into a blower thats airflow is tied only to rpm and not load. So, while the turbo will spool faster at X rpm under more load, the blower will just be spinning X rpm and will become a restriction to the turbo if the turbo is allowed to spool up at that throttle opening because the blowers flow is not changing with it. If the blower did not pose ANY restriction then the airflow from the turbo would be bypassing/recirculating through the valve back to the intake piping and not causing any 'boost' pressure in the piping.
You already fixed it in the time i forgot to check this thread, so that's good! 
It's cool that you came up with a different way to accomplish the controls on the bypass wastegate. Keep it up.
Yeah that all makes sense!
I think venting the lower side to atmo is the best thing i can do at wot. If my throttle body started to cause a restriction i would have more pressure on the cold side of throttle body that would push the bypass off its seat and leak.
Well today I tried to control the total boost and not just bounce of the boost protection.
I have all the springs I have in the wastegate. 7, 15 & 17 psi springs in there.
I'm getting a total of around 17-18 psi controlled boost right to the red line now. I need to introduce a pwm line to the upper side of the turbo wastegate now to up the boost.
I'm using total boost made to control the wastegate as it will be more accurate in the final figure made. I think!
Here's a quick pull, if you can see it?
From around 2500rpm. Only climbing a few hundred rpm but boost comes in pretty hard.
https://www.flickr.com/gp/157274311@N07/N60WDK
That's 22.5 psi in pretty quick fashion. Those glowshift gauges are rubbish. Way off...
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